Selecting the right storage technology for virtual environments depends largely on your environment's characteristics
and needs. There are many technologies available, spanning all levels of performance, functionality and price. One such technology, known as Openfiler, an open source storage management appliance, offers administrators flexibility at low cost. This tip tours Openfiler, which may offer a use case for certain virtual environments. I'll outline scenarios for using the Openfiler appliance as well.
Features, requirements and options
Openfiler is a versatile software image that can take general-purpose server hardware and convert it to a highly functional storage appliance. Openfiler has its roots in the open source community, and its business model is simple: The software is free, and users can pay for support offerings.
Although Openfiler has open source roots, support offerings are available for production implementations. The support offerings start at one year in duration, and round-the-clock service is available if needed.
Installation of Openfiler
Openfiler's installation is available in two main offerings: as a bare-metal installation or as a virtual appliance. The bare-metal option transforms a general-purpose server into a SAN storage system. The installation will be based on either the x86 or x64 Linux 2.6 kernel. Use the x64-based image if you are going this route for memory and performance reasons. The other option is to install Openfiler as a virtual appliance with VMware or Citrix.
First, let's go through the installation of Openfiler on a bare-metal system with the x64 edition. From the installation CD, the boot screen is a familiar starting place for Linux or VMware ESX installations. Figure 1 below shows the initial Openfiler installation screen:
The next steps include an optional media check, language selection and disk partitioning. Depending on your system configuration, you may want to set up separate arrays for configuration and disk groups. In this example, there is one disk available to the Openfiler installation, as Figure 2 indicates.
The storage provided to a virtual environment will be a different volume on the bare-metal hardware, discussed later. The installation now progresses to the networking configuration, which, again, is straightforward. Figure 3 shows an IP address being assigned to Openfiler.
The installation finally prompts for time-zone and root password configuration before installing the packages locally. Once the installation is complete, you can log into Openfiler's Web interface. The root password that was set during the installation is not helpful for storage provisioning in default configurations. The Openfiler username (the default password is "password") is used for this configuration. To provision storage, click on the Volumes tab, as Figure 4 shows.
Once a new physical volume is created, the dedicated disk for virtual platform storage will be formatted. Figure 5 shows the 100 GB disk about to be configured as an Openfiler volume.
Once formatted, the hdb partition is a volume ready for use in Openfiler. The disk is then configured to be a volume group, which I have named "iscsi1," as Figure 6 shows.
After a few additional configuration steps, the volume can be provisioned as storage to a virtualization platform. I selected iSCSI as the example configuration, and as Figure 7 shows, it is configured on Openfiler in the services section.
To provision a virtualization host to access the storage, host IP addresses need to be entered on the system tap, network configuration section. Figure 8 shows two virtualization hosts being added to the access list.
Adding Openfiler storage to VMware ESXi
The logical unit number (LUN) is configured like any other iSCSI storage resource in VMware ESXi. The iSCSI initiator for VMware ESX and ESXi systems is provided to the hypervisor by the VMkernel network interface. In the network configuration of the host, the iSCSI qualified name (IQN) for each host is specified. This unique identifier is used in Openfiler to grant permission to access a LUN via a mapping. In ESXi 3.5, the IQN number is retrieved from the storage adapters section of the host configuration. Figure 9 below shows this configuration.
This IQN number is entered into Openfiler as part of the mapping process and is shown in Figure J below.
A few steps are necessary to allow ESXi to re-enumerate the iSCSI storage. First, the iSCSI initiator may need to be enabled. This creates the IQN on the server if not already configured. Second, the iSCSI discovery and Challenge-Handshake Authentication Protocol (CHAP) settings -- if used -- need to be configured. The discovery would point to the IP address of the Openfiler server. Once these pieces are ready on ESXi, the LUN that was mapped from Openfiler is available to install and format with the vStorage Virtual Machine File System, or VMFS (a scan on the storage adapters will also occur on the configuration). Figure 11 shows the Openfiler LUN being pulled into ESXi.
At this point, the VMFS volume is ready to receive virtual machines and be used as a storage resource.
Software-based SANs should be used in environments where they make sense. A physical server can be loaded with a lot of disk and local array controller cache, it won't achieve the performance of a true SAN. But there are plenty of use cases for the Openfiler device, such as test and development environments and version testing with VMware's vSphere to use a SAN as a proving ground for the new vCenter Server and ESX platform.
About the author:
Rick Vanover (VCP, MCITP, MCSA) is a systems administrator at Safelite AutoGlass in Columbus, Ohio. He has over 12 years of IT experience and focuses on virtualization, Windows-based server administration and system hardware.